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Saturday, November 23, 2013

Electric blue icing

A glacier dripping down the cliff in Scott Inlet

Some time ago I promised I would write about the icebergs and glaciers I
saw this fall along the Baffin Island coast and in Scott Inlet.

In every gap between cliff faces in Scott Inlet, tongues of glaciers dripped in slow motion like icing on a cake of grey cliff. These weren't glaciers that could be accessed by fancy-big-wheeled buses like Columbia Glacier or even easily reached to trek across like these folks did. I wouldn't want to try to get up to the main part of the glaciers as even without the dripping ice, the cliff-gaps would have required us to use ropes to successfully scramble up.

Glaciers flow under their own weight, a direction that is obviously down hill. I have no idea how long it took, but a few of the glacier tongues had made it to the ocean calving bergy bits into the water. The icebergs in the inlet were tiny compared to the big icebergs moving south along the coast of Baffin Island.

Along the coast, the iceberg that sank the titanic once passed more than
a century ago. Even knowing before I arrived that I would be heading
into iceberg waters, I was surprised at how many there were. Some looked
large enough to dwarf an aircraft carrier (as a tangent: there was a
proposal in World War II to make aircraft carriers out of ice). Some
that had grounded could easily be mistaken for an island. Many had
wave-rounded forms reminiscent of modern sculpture, or ancient weathered
architecture.

An iceberg glowing blue

What fascinated me about the glaciers and icebergs was their colour. Even under the grey skies parts glowed electric blue – almost like they were generating their own light deep within. Glaciers and icebergs don't actually glow, but under the right light it looks that way.

Snow looks white because of all the reflective edges from the layers of snowflakes. Once the snow is compressed into glacier, the edges merge and air is pushed out. However, any ice can look blue in time. Like the reflective snowflake edges, air bubbles scatter all the wavelength of light making young ice look white. Older ice looks bluer because air bubbles and other impurities have been pushed out.

Like water, ice absorbs the longer wavelengths of light as it passes through. That is, the red end of the spectrum is absorbed first, which is why a short distance underwater the seascape is dominated by blues and greens. Ice has the same effect on light, it filters colours as light passes through leaving blues. And it appears to glow because those blues have passed the whole way through – so the ice looks bluest from the inside.

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About Me

I’m an oceanographer interested in a wide variety of other science topics. Here, I’ll occasionally write about my work but mostly, I’ll indulge the tangents that fascinate me on a smattering of topics. I have no intention of providing a precise summary of science and my views are bound to be flawed. I can be contacted at: bedard_jm[at]hotmail[dot]com